Brushes for Steel Mills and Metal Strip Lines: Selection Guide

1. Where brush rolls sit on a strip line

Each section has a different chemical, temperature and aggressiveness requirement, which is why one plant may run several brush roll designs.

• Pickling and descaling: abrasive brushes after the acid section help remove remaining scale and smut.
• Alkaline and electrolytic cleaning: brush scrubbers remove rolling oil, emulsion and iron fines before annealing, galvanizing or tinning.
• Hot-water rinse: brushes in the rinse section remove chemical residue.
• Coil coating pretreatment: abrasive cylinder brushes scrub the strip so primer and paint adhere.
• Finishing and deburring: abrasive brushes on flat sheet, including sheet with cut-outs.

2. Abrasive nylon vs wire vs plain synthetic

DuPont's brush-filament bulletin notes that abrasive filament brushes have been used to clean steel sheet before coating for more than 30 years, and that mixing fibreglass with abrasive nylon gives a very aggressive brush for removing residue from newly rolled sheet. See also our comparison of abrasive nylon vs wire wheel brushes.

3. Filament size and grit for sheet cleaning

DuPont gives these typical abrasive nylon choices for sheet metal work, in an environment described as hot (up to 85 °C / 185 °F) with caustic chemicals. They are a sensible starting point when specifying a new roll:

4. Heat and chemistry: why nylon 612

Strip cleaning sections are hot and alkaline, which is hard on any polymer. DuPont's data shows that alkaline solutions do not affect nylon below 38 °C but cause gradual deterioration above that, and that degradation roughly doubles for each 5 °C rise; the rate at 80 °C is about 64 times the rate at 50 °C. Nylon also becomes softer as it gets hotter: the bulletin notes stiffness drops by about another 50% at 60 °C compared with room temperature.

Nylon 612 is the usual base polymer because it absorbs only about 3% water at saturation against 8.5% for nylon 66, so it stays stiffer in wet sections. Silicon carbide is the most common grit; aluminium oxide is tougher and less likely to fracture, and ceramic grit is the most aggressive of the three. Silicon carbide grit for these filaments contains less than 0.1% iron oxide and no free iron, so it does not leave iron contamination on aluminium strip.

5. Roll construction

DuPont describes metal-strip construction (filament held in a metal channel and wound around a core) as the standard for cleaning and finishing flat sheet and coil, and calls it very durable. Other formats include disc-type rolls, where filled discs are stacked on a shaft, and modular sections that can be replaced without rebuilding the whole roll.

Relevant categories: steel strip and rolling mill brush rollers, spiral wound roller brushes and abrasive nylon brushes. Core design and balance are covered in how to choose a cylinder roller brush.

6. Wear, break-in and replacement

• Expect a break-in period: a new abrasive brush cuts hard at first, then settles as grit wears and the filament takes up moisture. DuPont says this can take from minutes to hours.
• As short-trim brushes wear down, filaments get shorter and stiffer, so the roll becomes more aggressive at the same setting. Adjust pressure rather than speed where possible.
• Measure the outside diameter at both ends and the centre regularly; uneven wear points to misalignment or uneven strip tension.
• Watch for filament breakage at the base, which is a sign of over-penetration or excessive flexing.
• Keep a spare roll per position on critical lines; changing a roll in a planned stop is cheaper than losing coating quality.

7. What to send for a quote

Send the information through Request a Quote. For large rolls, the factory will usually confirm the design on a drawing before production.

• Roll drawing: outside diameter, face length, core diameter, shaft journals, bearing seats and keyways.
• Line section, strip material (carbon steel, stainless, aluminium) and width.
• Bath chemistry, concentration and temperature; wet or dry running.
• Current fill (material, filament diameter, grit) and what you would like to change.
• Rotation speed and direction relative to strip travel, and annual quantity.

Frequently asked questions

What brush is used on a steel pickling line?

Abrasive nylon brush rolls (silicon carbide or aluminium oxide grit in nylon 612) are common after pickling to remove remaining scale and smut. Stainless wire rolls are used where more aggressive descaling is needed and surface marking is acceptable.

What grit should a strip cleaning brush roll use?

DuPont lists 80 or 120 grit on 1.02 mm filament, or 180 grit on 0.89 mm filament, for cleaning sheet metal, and 240 grit on 0.76 mm filament for finishing. Final choice depends on the surface you need and the line speed.

How hot can abrasive nylon brush rolls run?

DuPont describes typical sheet-cleaning use at up to 85 °C with caustic chemicals. Higher temperatures soften nylon and speed up chemical attack, so ask the factory to confirm the filament grade for your bath conditions.

Can silicon carbide brushes be used on aluminium strip?

Yes. According to DuPont, silicon carbide grit used in abrasive filament contains less than 0.1% iron oxide and no free iron, so it can be used on aluminium without causing iron contamination.

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